This invention concerns a headlight for vehicles of a type having a bowl-shaped light-transmissive shield and a housing of resinous plastic which is closed by the light-transmissive shield, with the housing having a receiving surface extending about a free peripheral edge thereof, which is arranged perpendicular to a mounting direction of the light-transmissive shield on the housing, on which a foot of the light-transmissive shield is mounted so as to have a large side clearance, perpendicular to the mounting direction, and with an attachment of the light-transmissive shield to the housing resulting from a pressure-applying, mechanical, device acting on the foot of the light-transmissive shield in the direction of the receiving surface.
Headlights are known from German Patent No. DE 35 40 130 Cl (commonly owned with the instant application) in which a foot of a bowl-shaped light-transmissive shield is placed in a U-shaped (in cross section) receiving channel of a housing. An adhesive is placed in the receiving channel before the light-transmissive shield is mounted therein which encloses the foot of the light-transmissive shield after the light-transmissive shield has been placed therein. After the adhesive has hardened, it provides a very strong coupling of the housing and the light-transmissive shield without additional mechanical elements and, further, the adhesive serves as a good sealing medium. However, it is disadvantageous that with a housing manufactured of resinous plastic the choice of the plastics is quite limited because not all resinous plastics, for example the thermoplastic polypropylene, can be adhered with an inexpensive adhesives. This disadvantage can be overcome with a mounting technology employed for a known headlight of German Patent DE 28 46 990 Al which is generally of a type as that of this application. A binding, or coupling, mass placed between a light-transmissive shield and a housing edge in the headlight of German Patent DE 28 46 990 Al is semi-fluid, or viscous, so that the adhering effect of this binding mass is quite small and the coupling mass serves mainly as a sealing medium. With this coupling technique it has been found that the light-transmissive shield, in its mount on the headlight, because of the fluidity of the sealing medium, wanders in the direction of a force applied thereto by gravity until an upper side of its foot contacts an inner leg, and/or a lower side contacts an outer leg, of a receiving channel. The danger of such a "wandering" of the light-transmissive shield is particularly great at high temperatures because the degree of firmness of the binding mass is than reduced. Also, a mechanical device formed by a locking nose on an outer leg of the receiving channel, which engages a step or shoulder in the light-transmissive shield and which locks the light-transmissive shield against movement in the mounting direction, does not prevent the light-transmissive shield from wandering downwardly.
A clearance between two legs of a U-shaped receiving channel is larger than a thickness of a foot of a light-transmissive shield and this increases with the size of a resinous plastic housing, and the clearance is particularly large if a particularly inexpensive plastic is used in the manufacture of the housing, where large tolerances arise for the housing. The large manufacturing tolerances of light-transmissive shields of pressed or molded glass also contribute to enlarging the receiver channel. In the known headlights of German Patent DE 28 46 990 Al the mechanical devices which lock the light-transmissive shield to the housing are spring loaded noses which are formed on the outer leg of the receiver channel and which engage in a step in the outer surface of the light-transmissive shield. In this manner the light-transmissive shield is only held to the housing against movement in a mounting direction.
German Gebrauchsmuster DE GM 76 26 043 discloses a headlight in which a rubber-like seal is placed in a U-shaped (in cross section) receiver channel. A foot of a light-transmissive channel is pressed on the rubber seal by a mechanical device. It is disadvantageous in this arrangement that the seal of rubber is a separate part, thereby cost intensifying the manufacturing thereof because it is either a molded seal or a extruded seal. Such on extruded seal must be cut to exactly correct lengths so that no unsealed portions are created along contact points. Additionally, the position of a light-transmissive shield must be accurately maintained thereon by a manufacturing apparatus until the mechanical device is mounted. The mechanical device is of a spring-steel manufactured, C-shaped, holding spring, one leg of which engages a step on the light-transmissive shield and the other leg of which engages a step on the housing. Further, this clamp must be constructed to be quite stable so that a pressure applied by the light-transmissive shield to the rubber seal is sufficiently high that the bulky seal is deformed by the foot of the light-transmissive shield to prevent the foot of the light-transmissive shield from wandering downwardly.
It is an object of this invention to provide a headlight of the general type set forth above to have a foot of a light-transmissive shield centered on a larger receiving surface, which is especially wider than is necessary for the thickness of the light-transmissive shield because of manufacturing tolerances, without the need of additional manufacturing parts or work operations, but yet the light-transmissive shield is maintained centered, or positioned, on the housing in a direction perpendicular to a mounting direction.